Hibernate：有了 save,为什么还需要 persist.doc

save 1 /** 2 * Persist the given transient instance, first assigning a generated identifier. (Or 3 * using the current value of the identifier property if the ttassigned/tt 4 * generator is used.) This operation cascades to associated instances if the 5 * association is mapped with {@code cascade=save-update} 6 * 7 * @param object a transient instance of a persistent class 8 * 9 * @return the generated identifier 10 */ 11 public Serializable save(Object object); persist 1 /** 2 * Make a transient instance persistent. This operation cascades to associated 3 * instances if the association is mapped with {@code cascade=persist} 4 * p/ 5 * The semantics of this method are defined by JSR-220. 6 * 7 * @param object a transient instance to be made persistent 8 */ 9 public void persist(Object object); 解释 save 因为需要返回一个主键值，因此会立即执行 insert 语句，而 persist 在事务外部调用时则不会立即执行 insert 语句，在事务内调用还是会立即执行 insert 语句的。 看 persist 的注释会觉得其不会立即执行 insert 语句，为何 在事务内调用会立即执行 insert 语句，后面再分析。 测试 SessionHelper 1 package demo; 2 3 import org.hibernate.*; 4 import org.hibernate.cfg.*; 5 6 public final class SessionHelper { 7 private static SessionFactory factory; 8 9 public static void execute(SessionAction action) { 10 execute(action, false); 11 } 12 13 public static void execute(SessionAction action, boolean beforeTransaction) { 14 Session session = openSession(); 15 try { 16 if (beforeTransaction) { 17 System.out.println(action); 18 action.action(session); 19 } 20 21 System.out.println(begin transaction); 22 session.beginTransaction(); 23 if (!beforeTransaction) { 24 System.out.println(action); 25 action.action(session); 26 } 27 28 System.out.println(flush and commit); 29 session.flush();